<HTML>
<HEAD>
<TITLE>Re: [Lustre-discuss] lustre file system with failover</TITLE>
</HEAD>
<BODY>
<FONT FACE="Verdana, Helvetica, Arial"><SPAN STYLE='font-size:12.0px'><BR>
Hi Trupti,<BR>
<BR>
It depends on how your failover is implemented. The bottom line is that if you have a transaction in-flight when your MDT is disconnected, all new transactions will block until queued and in-flight transactions either complete or time out. If your failover window is a few seconds or less, you shouldn’t notice more than a minor blip as the failover MDS recovers state for the downed MDS and finishes any transactions in progress.<BR>
<BR>
Your results will vary depending on the hardware you use and the settings of your failover; in one of my clusters, my failover window is actually quite long (about a minute and a half) due to the way the storage is implemented (the FC buses spend considerable time polling each visible LUN looking for the Lustre ones and I never bothered with device multi-pathing), but my transactions complete as expected once the MDT becomes active on the failover MDS.<BR>
<BR>
cheers,<BR>
Klaus<BR>
<BR>
On 6/11/08 5:07 AM, "trupti shete" <truptips86@yahoo.co.in>did etch on stone tablets:<BR>
<BR>
</SPAN></FONT><BLOCKQUOTE><FONT FACE="Verdana, Helvetica, Arial"><SPAN STYLE='font-size:12.0px'>Hi<BR>
I am very new to lustre file system. <BR>
I want to know how can I test whether the failover is working or not?<BR>
<BR>
I am having the following scenario of lustre file system-- <BR>
MGS- /dev/sdb on node1 and failnode node2<BR>
MDT- /dev/sdc on node1 and failnode node2<BR>
(I am using iSCSI for the sharing discs /dev/sdb & /dev/sdc between node1 & node2)<BR>
OST1- /dev/sda1 on node2<BR>
OST2- /dev/sda2 on node2<BR>
And there are 3 clients.<BR>
<BR>
If client1 opens a file to write and at that time if I umount the MDT (which will be mounted on node1) will node2 take care of? Will client1 experience any difference?<BR>
<BR>
-Trupti<BR>
<BR>
<BR>
<HR ALIGN=CENTER SIZE="1" WIDTH="100%"> Explore your hobbies and interests. Click here to begin. <a href="http://in.rd.yahoo.com/tagline_groups_6/*http://in.promos.yahoo.com/groups/"><http://in.rd.yahoo.com/tagline_groups_6/*http://in.promos.yahoo.com/groups/></a> <BR>
<HR ALIGN=CENTER SIZE="3" WIDTH="95%"></SPAN></FONT><FONT SIZE="2"><FONT FACE="Monaco, Courier New"><SPAN STYLE='font-size:10.0px'>_______________________________________________<BR>
Lustre-discuss mailing list<BR>
Lustre-discuss@lists.lustre.org<BR>
<a href="http://lists.lustre.org/mailman/listinfo/lustre-discuss">http://lists.lustre.org/mailman/listinfo/lustre-discuss</a><BR>
</SPAN></FONT></FONT></BLOCKQUOTE><FONT SIZE="2"><FONT FACE="Monaco, Courier New"><SPAN STYLE='font-size:10.0px'><BR>
</SPAN></FONT></FONT>
</BODY>
</HTML>